 /*
  * $Header: /cvshome/build/org.osgi.service.permissionadmin/src/org/osgi/service/permissionadmin/PermissionInfo.java,v 1.16 2006/06/16 16:31:44 hargrave Exp $
  *
  * Copyright (c) OSGi Alliance (2001, 2006). All Rights Reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  * http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 package org.osgi.service.permissionadmin;

 /**
  * Permission representation used by the Permission Admin service.
  *
  * <p>
  * This class encapsulates three pieces of information: a Permission <i>type
  * </i> (class name), which must be a subclass of
  * <code>java.security.Permission</code>, and the <i>name </i> and <i>actions
  * </i> arguments passed to its constructor.
  *
  * <p>
  * In order for a permission represented by a <code>PermissionInfo</code> to be
  * instantiated and considered during a permission check, its Permission class
  * must be available from the system classpath or an exported package. This
  * means that the instantiation of a permission represented by a
  * <code>PermissionInfo</code> may be delayed until the package containing its
  * Permission class has been exported by a bundle.
  *
  * @version $Revision: 1.16 $
  */
 public class PermissionInfo {
     private String type;
     private String name;
     private String actions;

     /**
      * Constructs a <code>PermissionInfo</code> from the specified type, name, and
      * actions.
      *
      * @param type The fully qualified class name of the permission represented
      * by this <code>PermissionInfo</code>. The class must be a subclass
      * of <code>java.security.Permission</code> and must define a
      * 2-argument constructor that takes a <i>name </i> string and an
      * <i>actions </i> string.
      *
      * @param name The permission name that will be passed as the first argument
      * to the constructor of the <code>Permission</code> class identified
      * by <code>type</code>.
      *
      * @param actions The permission actions that will be passed as the second
      * argument to the constructor of the <code>Permission</code> class
      * identified by <code>type</code>.
      *
      * @throws java.lang.NullPointerException if <code>type</code> is
      * <code>null</code>.
      * @throws java.lang.IllegalArgumentException if <code>action</code> is not
      * <code>null</code> and <code>name</code> is <code>null</code>.
      */
     public PermissionInfo(String type, String name, String actions) {
         this.type = type;
         this.name = name;
         this.actions = actions;
         if (type == null) {
             throw new NullPointerException ("type is null");
         }
         if ((name == null) && (actions != null)) {
             throw new IllegalArgumentException ("name missing");
         }
     }

     /**
      * Constructs a <code>PermissionInfo</code> object from the specified encoded
      * <code>PermissionInfo</code> string. White space in the encoded
      * <code>PermissionInfo</code> string is ignored.
      *
      *
      * @param encodedPermission The encoded <code>PermissionInfo</code>.
      * @see #getEncoded
      * @throws java.lang.IllegalArgumentException If the
      * <code>encodedPermission</code> is not properly formatted.
      */
     public PermissionInfo(String encodedPermission) {
         if (encodedPermission == null) {
             throw new NullPointerException ("missing encoded permission");
         }
         if (encodedPermission.length() == 0) {
             throw new IllegalArgumentException ("empty encoded permission");
         }
         try {
             char[] encoded = encodedPermission.toCharArray();
             int length = encoded.length;
             int pos = 0;
             
             /* skip whitespace */
             while (Character.isWhitespace(encoded[pos])) {
                 pos++;
             }
             
             /* the first character must be '(' */
             if (encoded[pos] != '(') {
                 throw new IllegalArgumentException (
                         "expecting open parenthesis");
             }
             pos++;

             /* skip whitespace */
             while (Character.isWhitespace(encoded[pos])) {
                 pos++;
             }
             
             /* type is not quoted or encoded */
             int begin = pos;
             while (!Character.isWhitespace(encoded[pos]) && (encoded[pos] != ')')) {
                 pos++;
             }
             if (pos == begin || encoded[begin] == '"') {
                 throw new IllegalArgumentException ("expecting type");
             }
             this.type = new String (encoded, begin, pos - begin);
             
             /* skip whitespace */
             while (Character.isWhitespace(encoded[pos])) {
                 pos++;
             }
             
             /* type may be followed by name which is quoted and encoded */
             if (encoded[pos] == '"') {
                 pos++;
                 begin = pos;
                 while (encoded[pos] != '"') {
                     if (encoded[pos] == '\\') {
                         pos++;
                     }
                     pos++;
                 }
                 this.name = unescapeString(encoded, begin, pos);
                 pos++;

                 if (Character.isWhitespace(encoded[pos])) {
                     /* skip whitespace */
                     while (Character.isWhitespace(encoded[pos])) {
                         pos++;
                     }
                     
                     /* name may be followed by actions which is quoted and encoded */
                     if (encoded[pos] == '"') {
                         pos++;
                         begin = pos;
                         while (encoded[pos] != '"') {
                             if (encoded[pos] == '\\') {
                                 pos++;
                             }
                             pos++;
                         }
                         this.actions = unescapeString(encoded, begin, pos);
                         pos++;

                         /* skip whitespace */
                         while (Character.isWhitespace(encoded[pos])) {
                             pos++;
                         }
                     }
                 }
             }
             
             /* the final character must be ')' */
             char c = encoded[pos];
             pos++;
             while ((pos < length) && Character.isWhitespace(encoded[pos])) {
                 pos++;
             }
             if ((c != ')') || (pos != length)) {
                 throw new IllegalArgumentException ("expecting close parenthesis");
             }
         }
         catch (ArrayIndexOutOfBoundsException e) {
             throw new IllegalArgumentException ("parsing terminated abruptly");
         }
     }

     /**
      * Returns the string encoding of this <code>PermissionInfo</code> in a form
      * suitable for restoring this <code>PermissionInfo</code>.
      *
      * <p>
      * The encoded format is:
      *
      * <pre>
      * (type)
      * </pre>
      *
      * or
      *
      * <pre>
      * (type &quot;name&quot;)
      * </pre>
      *
      * or
      *
      * <pre>
      * (type &quot;name&quot; &quot;actions&quot;)
      * </pre>
      *
      * where <i>name</i> and <i>actions</i> are strings that are encoded for
      * proper parsing. Specifically, the <code>"</code>,<code>\</code>, carriage
      * return, and linefeed characters are escaped using <code>\"</code>,
      * <code>\\</code>,<code>\r</code>, and <code>\n</code>, respectively.
      *
      * <p>
      * The encoded string contains no leading or trailing whitespace
      * characters. A single space character is used between <i>type</i> and
      * &quot;<i>name</i>&quot; and between &quot;<i>name</i>&quot; and &quot;<i>actions</i>&quot;.
      *
      * @return The string encoding of this <code>PermissionInfo</code>.
      */
     public final String getEncoded() {
         StringBuffer output = new StringBuffer (
                 8
                         + type.length()
                         + ((((name == null) ? 0 : name.length()) + ((actions == null) ? 0
                                 : actions.length())) << 1));
         output.append('(');
         output.append(type);
         if (name != null) {
             output.append(" \"");
             escapeString(name, output);
             if (actions != null) {
                 output.append("\" \"");
                 escapeString(actions, output);
             }
             output.append('\"');
         }
         output.append(')');
         return output.toString();
     }

     /**
      * Returns the string representation of this <code>PermissionInfo</code>. The
      * string is created by calling the <code>getEncoded</code> method on this
      * <code>PermissionInfo</code>.
      *
      * @return The string representation of this <code>PermissionInfo</code>.
      */
     public String toString() {
         return getEncoded();
     }

     /**
      * Returns the fully qualified class name of the permission represented by
      * this <code>PermissionInfo</code>.
      *
      * @return The fully qualified class name of the permission represented by
      * this <code>PermissionInfo</code>.
      */
     public final String getType() {
         return type;
     }

     /**
      * Returns the name of the permission represented by this
      * <code>PermissionInfo</code>.
      *
      * @return The name of the permission represented by this
      * <code>PermissionInfo</code>, or <code>null</code> if the permission
      * does not have a name.
      */
     public final String getName() {
         return name;
     }

     /**
      * Returns the actions of the permission represented by this
      * <code>PermissionInfo</code>.
      *
      * @return The actions of the permission represented by this
      * <code>PermissionInfo</code>, or <code>null</code> if the permission
      * does not have any actions associated with it.
      */
     public final String getActions() {
         return actions;
     }

     /**
      * Determines the equality of two <code>PermissionInfo</code> objects.
      *
      * This method checks that specified object has the same type, name and
      * actions as this <code>PermissionInfo</code> object.
      *
      * @param obj The object to test for equality with this
      * <code>PermissionInfo</code> object.
      * @return <code>true</code> if <code>obj</code> is a <code>PermissionInfo</code>,
      * and has the same type, name and actions as this
      * <code>PermissionInfo</code> object; <code>false</code> otherwise.
      */
     public boolean equals(Object obj) {
         if (obj == this) {
             return true;
         }
         if (!(obj instanceof PermissionInfo)) {
             return false;
         }
         PermissionInfo other = (PermissionInfo) obj;
         if (!type.equals(other.type) || ((name == null) ^ (other.name == null))
                 || ((actions == null) ^ (other.actions == null))) {
             return false;
         }
         if (name != null) {
             if (actions != null) {
                 return name.equals(other.name) && actions
                         .equals(other.actions);
             }
             else {
                 return name.equals(other.name);
             }
         }
         else {
             return true;
         }
     }

     /**
      * Returns the hash code value for this object.
      *
      * @return A hash code value for this object.
      */
     public int hashCode() {
         int hash = type.hashCode();
         if (name != null) {
             hash ^= name.hashCode();
             if (actions != null) {
                 hash ^= actions.hashCode();
             }
         }
         return hash;
     }

     /**
      * This escapes the quotes, backslashes, \n, and \r in the string using a
      * backslash and appends the newly escaped string to a StringBuffer.
      */
     private static void escapeString(String str, StringBuffer output) {
         int len = str.length();
         for (int i = 0; i < len; i++) {
             char c = str.charAt(i);
             switch (c) {
                 case '"' :
                 case '\\' :
                     output.append('\\');
                     output.append(c);
                     break;
                 case '\r' :
                     output.append("\\r");
                     break;
                 case '\n' :
                     output.append("\\n");
                     break;
                 default :
                     output.append(c);
                     break;
             }
         }
     }

     /**
      * Takes an encoded character array and decodes it into a new String.
      */
     private static String unescapeString(char[] str, int begin, int end) {
         StringBuffer output = new StringBuffer (end - begin);
         for (int i = begin; i < end; i++) {
             char c = str[i];
             if (c == '\\') {
                 i++;
                 if (i < end) {
                     c = str[i];
                     switch (c) {
                         case '"' :
                         case '\\' :
                             break;
                         case 'r' :
                             c = '\r';
                             break;
                         case 'n' :
                             c = '\n';
                             break;
                         default :
                             c = '\\';
                             i--;
                             break;
                     }
                 }
             }
             output.append(c);
         }
         
         return output.toString();
     }
 }

